From 0d3ac4b182c6815182b49b1717e3ceb488ff17b2 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Thu, 29 Mar 2012 09:57:45 -0400 Subject: [PATCH] Btrfs: fix recursive defragment with autodefrag option $ mkfs.btrfs disk $ mount disk /mnt -o autodefrag $ dd if=/dev/zero of=/mnt/foobar bs=4k count=10 2>/dev/null && sync $ for i in `seq 9 -2 0`; do dd if=/dev/zero of=/mnt/foobar bs=4k count=1 \ seek=$i conv=notrunc 2> /dev/null; done && sync then we'll get to defrag "foobar" again and again. So does option "-o autodefrag,compress". Reasons: When the cleaner kthread gets to fetch inodes from the defrag tree and defrag them, it will dirty pages and submit them, this will comes to another DATA COW where the processing inode will be inserted to the defrag tree again. This patch sets a rule for COW code, i.e. insert an inode when we're really going to make some defragments. Signed-off-by: Liu Bo Signed-off-by: Chris Mason --- fs/btrfs/inode.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index eb6aec7bbacb5..1be31368e881a 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -347,8 +347,9 @@ static noinline int compress_file_range(struct inode *inode, int will_compress; int compress_type = root->fs_info->compress_type; - /* if this is a small write inside eof, kick off a defragbot */ - if (end <= BTRFS_I(inode)->disk_i_size && (end - start + 1) < 16 * 1024) + /* if this is a small write inside eof, kick off a defrag */ + if ((end - start + 1) < 16 * 1024 && + (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size)) btrfs_add_inode_defrag(NULL, inode); actual_end = min_t(u64, isize, end + 1); @@ -843,7 +844,8 @@ static noinline int cow_file_range(struct inode *inode, ret = 0; /* if this is a small write inside eof, kick off defrag */ - if (end <= BTRFS_I(inode)->disk_i_size && num_bytes < 64 * 1024) + if (num_bytes < 64 * 1024 && + (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size)) btrfs_add_inode_defrag(trans, inode); if (start == 0) { -- 2.39.5